<template>
	<view>
    <!-- 使用自定义的搜索组件 -->
    <my-search @myclick="gotoSearch"></my-search>
		<view class="scroll-view-container">
		  <!-- 左侧的滑动区 -->
      <scroll-view class="left-scroll-view" scroll-y="true" :style="{height: wh + 'px'}">
        <block v-for="(item,i) in cateList" :key="i">
          <!-- 三元表达式？和：后要加空格 -->
          <view :class="['left-scroll-view-item',i === active? 'active': '']" @click="activeChange(i)">{{item.cat_name}}</view>
        </block>
      </scroll-view>
      <!-- 右侧的滑动区 -->
      <scroll-view class="right-scroll-view" scroll-y="true" :style="{height: wh + 'px'}" :scroll-top="scrollTop">
        <view class="cate-lv2" v-for="(item2,i2) in catelevel2" :key="i2">
          <!-- 二级分类的标题 -->
          <view class="cate-lv2-title">/{{item2.cat_name}}/</view>
          <!-- 三级分类列表 -->
          <view class="cate-lv3-list">
            <view class="cate-lv3-item" v-for="(item3,i3) in item2.children" :key="i3" @click="gotoGoodsList(item3)">
              <image :src="item3.cat_icon"></image>
              <text>{{item3.cat_name}}</text>
            </view>
          </view>
        </view>
      </scroll-view>
		</view>
	</view>
</template>

<script>
	export default {
		data() {
			return {
				// 当前设备可用的高度
        wh: 0,
        active: 0,
        //scrollTop代表距离顶部的的像素
        scrollTop: 0,
        cateList: [],
        catelevel2: []
			};
		},
    onLoad() {
      const sysInfo = uni.getSystemInfoSync()
      // 减去搜索区域50像素
      this.wh = sysInfo.windowHeight - 50
      
      this.getCateList()
    },
    methods:{
      // 获取分类列表的数据
      async getCateList(){
        const {data:res} = await uni.$http.get('/api/public/v1/categories')
        if(res.meta.status !== 200) return uni.$showMsg()
        this.cateList = res.message
        //为二级分类赋值
        this.catelevel2 = res.message[0].children
      },
      //切换一级分类
      activeChange(i){
        this.active = i
        //重新为二级分类赋值
        this.catelevel2 = this.cateList[i].children
        this.scrollTop = this.scrollTop === 0? 1 : 0
      },
      //跳转到商品列表页面
      gotoGoodsList(item){
        uni.navigateTo({
          url: '/subpkg/goods_list/goods_list?cid=' + item.cat_id
        })
      },
      //跳转到搜索页面
      gotoSearch(){
        uni.navigateTo({
          url: '/subpkg/search/search'
        })
      }
    }
	}
</script>

<style lang="scss">
.scroll-view-container{
  display: flex;
}
.left-scroll-view{
  width: 120px;
}
.left-scroll-view-item{
  background-color: #F7F7F7;
  line-height: 60px;
  text-align: center;
  font-size: 12px;
  // 既有left-scroll-view-item类名也有active类名
  &.active{
    background-color: #FFFFFF;
    position: relative;
    //表示在前面添加一个类
    &::before{
      //content一定要设置
      content: ' ';
      display: block;
      width: 3px;
      height: 30px;
      background-color: #C00000;
      position: absolute;
      //使元素的顶边框距离父元素50%的距离
      top: 50%;
      left: 0;
      //再往上移动自身高度的50%，完成居中对齐
      transform: translateY(-50%);
    }
  }
}
.cate-lv2-title{
  font-size: 12px;
  font-weight: bold;
  text-align: center;
  padding: 15px 0;
}
.cate-lv3-list{
  display: flex;
  flex-wrap: wrap;
  
  .cate-lv3-item{
    width: 33.33%;
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 10px;
    
    image{
      width: 60px;
      height: 60px;
    }
    text{
      font-size: 12px;
    }
  }
}

</style>
